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Breastfeeding or formula: New evidence or just the media crying wolf?

By Laurén Doamekpor. Updated June 2014.

Deciding whether to breastfeed or formula-feed is probably one of the first choices expectant parents have to make and has led to a heated debate between supporters of each side.

Research shows that compared to formula-fed babies, children who are breastfed are more protected from diseases including allergies and infections and are less likely to become obese or diabetic. Based on this research, the American Academy of Pediatrics and the World Health Organization (WHO) advise women to breastfeed exclusively for 6 months.12 Breastfeeding can also lower a woman’s risk of breast cancer.3 Even though breastfeeding has health benefits for babies and their mothers, not all women can breastfeed. There are many reasons why a mother may be unable to breastfeed, including not being able to make enough milk and a work schedule that doesn’t allow it. As a result, the issue of breastfeeding has become a contentious “what’s-best-for-baby” public debate.

The study conducted by Cynthia Colen and David Ramey from the Department of Sociology at Ohio State University used data that was collected over 10 years from 8,237 breastfed and formula-fed children aged 4 to 14.

The study was done in 2 steps. First, the researchers looked at differences between all the breastfed and formula-fed children. They measured differences in their 1) bodies and health status (body mass index, obesity, and asthma); 2) behavior (hyperactivity, attachment and behavioral compliance); and 3) academic achievement (reading comprehension, memory, vocabulary and academic performance).

In the second step, the researchers looked at differences the same way, but compared siblings from families where one was breastfed and another was formula-fed. By comparing siblings, the researchers were able to make sure that the children came from the same background: differences in the two children would be more likely to be the related to how they were fed instead of differences in family income, the mother’s level of education, or whether she worked or not.

What did the study find?

When the researchers simply compared all the breastfed children in the study to all the formula-fed ones, they found that the breastfed children did better on every measurement except for asthma. When they compared siblings where one was breastfed and the other was formula-fed, the researchers found that the breastfed children did better on 7 of the 11 outcomes but the results were not statistically significant (there was more than a 95% possibility that the differences found were due to chance). The researchers suggested that by comparing siblings, their study was able to isolate the impact of breastfeeding alone, unlike in other studies. In other studies, even when researchers took into account differences in the mothers’ income and education, there may have been other differences besides what the baby was drinking that contributed to breastfeeding babies scoring better, such as the style of mothering.

What else should you know?

This study got a lot of attention because the media ran with it, drawing a hasty conclusion sure to anger some and comfort others, without looking carefully at the research. Comparing siblings is definitely an interesting way to study the effects of breastfeeding. But there are a few things that the researchers did not take into account which leave unanswered questions about what the results of the study really mean:

The authors didn’t take into account the reason why the mothers breastfed one sibling and not the other. Did some mothers have difficulty breastfeeding? There may be other factors that caused mothers to formula-feed one child and not the other that were not taken into account in the study. On the other hand, if women formula fed a child because she was working full-time or too stressed or ill to breastfeed, one would expect those influences to have a negative impact on the baby and thus increase the differences between a formula fed and breastfed baby, not minimize them (as was reported in the study).

The researchers did not measure whether the children who were breastfed, were ONLY breastfed, or if their mothers alternated between breast milk and formula. Since experts recommend exclusive breastfeeding for the first 6 months, this information is important to know when thinking about the impact of the study results.

The authors focused on certain physical and academic measures, but did not include two outcomes where the evidence for breastfeeding’s benefits has been consistently strong: allergies and diabetes.

Did the media overreact? There are still too many unanswered questions to say that breastfeeding is no better for a baby than bottle feeding. And, breastfeeding isn’t just about babies; it also delivers health benefits to the mothers who do it. Breastfeeding can lower the risk of ovarian and breast cancer, help women return to their pre-pregnancy weight and help build a close relationship between mother and child. Read here for more information about the breastfeeding benefits for mothers and their babies.

American Academy of Pediatrics. Policy Statement. Breastfeeding and the Use of Human Milk. http://pediatrics.aappublications.org/content/129/3/e827.full#content-block ▲

Colen CG, Ramey DM. Is Breast Truly Best? Estimating the Effects of Breastfeeding on Long-term Child Health and Wellbeing in the United States Using Sibling Comparisons. Social Science & Medicine. 2014. doi: 10.1016/j.socscimed.2014.01.027. ▲